Optimized thumbnail generation: If the image was not edited yet anyway, only the (fast) raw internal preview image is taken. So if you just downloaded the many pictures from the camera, your machine will not busy generating thumbnails.

rtgui/filebrowserentry.cc

@@ -81,9 +81,9 @@ void FileBrowserEntry::refreshThumbnailImage () {
 }
 
 void FileBrowserEntry::refreshQuickThumbnailImage () {
-
+	// Only make a (slow) processed preview if the picture has been edited at all
     if ( thumbnail &&
-			thumbnail->isQuick() )
+			thumbnail->isQuick() && thumbnail->isPParamsValid() )
 	{
 		thumbImageUpdater->add(thumbnail, thumbnail->getProcParams(), preh, &updatepriority, true, this);    
 	}